This is definitely not something I would recommend. In fact I don't recommend keeping unspayed females.
The only time that this works is when the female is too young to be spayed and her hormones haven't kicked in. Then as soon as she was ready you would have to spay or it will all end in tears. Unspayed females in groups or pairs can be very aggressive (and if kept on their own of course too).
This is a no brainer - all bunnies should be neutered.